In the image intensifiers with the micro-channel plate used for multiplication of electrons, feedback of ions of Cs and/or residual gas from the inside of the micro-channel plate to a photocathode has been hitherto known as a factor to degrade life characteristics. For dealing with this problem, for example, in the case of the device described in Patent Literature 1, a film of metal such as Al (ion barrier film) is formed so as to cover the front surface of the micro-channel plate.